Passive leak detection for building water supply

ABSTRACT

A method and system for detecting small leaks in a plumbing system is disclosed. A temperature sensor coupled to the water in the plumbing system is used to determine if there is a leak. During times of inactivity for fixtures in the plumbing systems, a flow sensor might measure usage of water that would indicate a leak. For very small leaks, the flow is below a minimum measurable flow of the flow sensor. Embodiments of the invention measure temperature of water within a pipe coupled to the plumbing system. Temperature will generally decay in a particular predicable way when there is flow as the temperature of water upon entry to the building is lower than the air temperature within the building. Signal processing, machine learning and/or statistical approaches are used to analyze the temperature and optionally flow and/or pressure over time to determine when a leak is likely.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/818,562, filed on Nov. 20, 2017, entitled “Passive Leak Detection ForBuilding Water Supply,” the disclosure of which is hereby incorporatedby reference in its entirety for all purposes.

BACKGROUND

This disclosure relates in general to detecting pipe leaks and, but notby way of limitation, to use of in-line sensors for detection of smallleaks.

Homes and commercial buildings have water distributed throughout withvarious pipes and egress regulated with plumbing fixtures. It is notuncommon for there to be leaks as there are multiple points of failurein any water distribution system. For example, water pipes exposed tofreezing temperatures are prone to bursting with the expansion of ice.Leaks cause tremendous property damage, promote toxic mold growth andneedlessly waste water.

Detection of leaks in plumbing is notoriously difficult. Often the firstsign of a problem is flooding. There are flow sensors that measuremovement of liquid, but detection of leaks, especially small ones, is avexing problem. Although a small leak may never result in noticeableflooding, it can nurture growth of toxic mold and eventually progress toa large leak causing various water damage.

SUMMARY

Embodiments the plumbing analyzer use temperature and/or pressuresensors to determine when minute flows are occurring in the plumbing.One or more temperature and pressure sensors are thermally coupled tothe liquids within the plumbing. Different configuration plumbingsystems may use different algorithms to process the temperature and/orpressure sensor information to accurately detect leaks. Signalprocessing of the temperature sensor and optionally pressure and/or flowsensors allow recognizing when a minute flow in the pipe is most likelya leak and not normal usage. Some embodiments use pressure sensing tospectrally determine when there is a leak in the plumbing system.

In one embodiment, the present disclosure provides a method and systemfor detecting small leaks in a plumbing system. Temperature sensor(s)and/or pressure sensor(s) coupled to the water in the plumbing system isused to determine if there is a leak. During times of inactivity forfixtures in the plumbing systems, a flow sensor might measure usage ofwater that would indicate a leak. For very small leaks, the flow isbelow a minimum measurable flow of the flow sensor. Embodiments of theinvention measure temperature of water within a pipe coupled to theplumbing system. Temperature will generally decay in a particularpredicable way when there is flow as the temperature of water upon entryto the building is lower than the air temperature within the building.Similarly, pressure will generally decay in certain plumbing systemconfigurations as the leak depletes water from the pipes. Spectralanalysis of the pressure data can detect changes in the spectraassociated with the leak in some plumbing systems. Signal processing,machine learning and/or statistical approaches are used to analyze thetemperature and optionally flow and/or pressure over time to determinewhen a leak is likely.

In one embodiment, a method for detecting small leaks of liquid in aplumbing system is disclosed. Liquid flow is measured within a pipe ofthe plumbing system with a flow sensor. Determining algorithmicallyusing the flow sensor that there is no intentional liquid egress fromthe plumbing system with an open water fixture. A temperature of theliquid is measured over time at a point in the plumbing system upstreamfrom a leak while there is no intentional liquid egress and no measuredflow with the flow sensor. Measuring temperature over time to determinedecay of the measured temperature exceeds threshold decay of liquid inthe plumbing system. A leak detected signal is transmitted when thedecay exceeds a threshold decay.

Some embodiments use signal processing techniques to match the measuredtemperature to a leak profile. Other embodiments, measure temperature ata second point of the plumbing system and process a second measuredtemperature at the second point before correcting the processing themeasured temperature using the second measured temperature. In someinstallations, the measuring temperature at the second point ismeasuring air temperature away from the liquid.

One embodiment determines air temperature within a building hosting theplumbing system, where the decay is a function of the air temperature. Athermal mass of the plumbing system can be determined over time todetermine the predicted decay. In one embodiment, the flow through theleak in the pipe is below a perceptible limit of the flow sensor.

Further areas of applicability of the present disclosure will becomeapparent from the detailed description provided hereinafter. It shouldbe understood that the detailed description and specific examples, whileindicating various embodiments, are intended for purposes ofillustration only and are not intended to necessarily limit the scope ofthe disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is described in conjunction with the appendedfigures:

FIG. 1 depicts a block diagram of an embodiment of a water analysissystem;

FIG. 2 depicts a block diagram of an embodiment of a water device;

FIG. 3 depicts a block diagram of an embodiment of a cloud analyzer;

FIG. 4 depicts a block diagram of an embodiment of a plumbing system;

FIG. 5 depicts a diagram of an embodiment of an installed water device;

FIGS. 6A and 6B depict charts for different temperature sensingconditions;

FIGS. 7A and 7B depict charts for different pressure sensing conditions;

FIG. 8 illustrates a flow chart of an embodiment of a process fordetecting leaks;

FIG. 9A illustrates a flow chart of an embodiment of a process foranalyzing temperature sensor readings to detect a leak; and

FIGS. 9B-9C depict flow charts of an embodiment of a process foranalyzing pressure sensor readings to detect leaks.

In the appended figures, similar components and/or features may have thesame reference label. Further, various components of the same type maybe distinguished by following the reference label by a dash and a secondlabel that distinguishes among the similar components. If only the firstreference label is used in the specification, the description isapplicable to any one of the similar components having the same firstreference label irrespective of the second reference label.

DETAILED DESCRIPTION

The ensuing description provides preferred exemplary embodiment(s) only,and is not intended to limit the scope, applicability or configurationof the disclosure. Rather, the ensuing description of the preferredexemplary embodiment(s) will provide those skilled in the art with anenabling description for implementing a preferred exemplary embodiment.It is understood that various changes may be made in the function andarrangement of elements without departing from the spirit and scope asset forth in the appended claims.

A plumbing analyzer finds small leaks that are not detected by aconventional flow sensor. For example, turbine flow meters don't sensebelow 0.7 gpm and ultrasonic flow sensors have resolution down to0.1-0.2 gpm. Statistical approaches and signal processing techniquesprocess temperature readings for the leak detection by relying onvariations of the temperature signal to provide first insights into thepossibility of a leak with pressure and/or flow sensing optionallyassisting in validating the likelihood of a leak in a plumbing system.Embodiments allow detection of leaks below 0.7 gpm and as low as 0.06gpm.

When water is stagnant in the pipes (i.e., there is no intentional wateregress or leaks) the temperature of water varies based on the locationthe water device is installed and the temperature of the water supplyentering the building. Where the water device is installed inside abuilding, for example, the temperature will stabilize at the ambienttemperature typically regulated by a HVAC thermostat. On the other hand,if the plumbing analyzer is placed outdoors it will vary as the weatherchanges over the course of the day. For small flows that are notdetected by conventional flow sensors, there is a change in thetemperature noted by the plumbing analyzer. Depending on the rate ofwater flow the temperature stabilizes at a certain temperature.

The city supplied water temperature varies relatively slowly since theyare typically delivered via pipes which are buried underground. Sincethese pipes are buried underground there is less variation intemperature as compared to the atmospheric temperature. Ground watertemperatures vary slightly from around 40 to 55° F. (4 to 13° C.). Suchtemperature changes are dependent upon well depth and abovegroundstorage facilities. Surface water temperatures vary with seasonal changefrom around 40 to 80° F. (4 to 27° C.) with even higher temperatures inthe deep South and Southwest. It can be said that the city suppliedwater temperature remains relatively stable during a given season for agiven location (Temperature varies from 38° F. in Anchorage, Ak. to 82°F. in Phoenix, Ariz.). The temperature changes noted by the water deviceare due to water flowing through the pipes and can help detect smallunintended water usages or leaks continuously without engaging theshut-off-valve or other techniques that actively engage the plumbingsystem as described in application Ser. No. 15/344,458, Entitled “SYSTEMAND METHOD FOR LEAK CHARACTERIZATION AFTER SHUTOFF OF PRESSURIZATIONSOURCE,” filed on Nov. 4, 2016, which is incorporated by reference forall purposes.

Pressure in the plumbing system can be analyzed with the water device.The municipal water system is pressurized so that the plumbing fixturesdispense water when opened. The water main into the building istypically at 80-120 psi. Most buildings buffer the water main pressurewith a pressure reducing valve (PRV) to lower the pressure to 40-70 psi,which also isolates noise seen with sensors when connected directly tothe water main. Within the building, temperature and pressure willstabilize at a given rate of flow caused by leak or other egress fromthe plumbing system even for situations with the flow sensor cannotperceive anything.

Referring first to FIG. 1, a block diagram of an embodiment of a wateranalysis system 100 is shown. The municipal water system 128 isconnected to the building 112 with a water main 150, but otherembodiments could source their water from a well, a cistern, a tank, orany other source. Different water sources may use different flow andleak detection algorithms.

Remote from the building 112 over the Internet 104 is a cloud analyzer108 that is in communication with various buildings and user devices130. User account information, sensor data, local analysis, municipalwater usage information for the building 112 is passed to the cloudanalyzer 108. User devices 130 may connect with the water device 120 andthe cloud analyzer through a local network 134 and/or a cellularnetwork. The water device 120 can have an Ethernet, a broadband overpower line, a WiFi, and/or a cellular connection coupled to the cloudanalyzer 108. Some embodiments include a gateway or peer node that thewater device can connect to that is coupled to the network 134 and/orInternet 104 using WiFi, Bluetooth, Zigbee, or other short rangewireless signals. Generally, there is a gateway or firewall between thenetwork 134 and the Internet 104.

Within the building 112, the plumbing system 116 is a collection ofpipes connected to appliances and fixtures all coupled to the water main150. A building may have one or more water device(s) 120 in fluidcommunication with the plumbing system 116. A water device 120 may becoupled to the cold and/or hot water pipe at a particular location andwirelessly or wire communicates with the network 134.

One or more point interface(s) 124 may or may not be in fluidcommunication with the plumbing system, but can gather data in someembodiments such as ambient temperature, temperature outside the pipe,and/or acoustic waves inside or outside the pipe. The point interfaces124 are coupled to the network 134 to allow input and output to the userwith an interface. The point interface may be separate from the plumbingsystem 116 altogether while providing status on the water analysissystem 100 such as instantaneous water usage, water usage over a timeperiod, water temperature, water pressure, etc. Error conditions such asleaks, running toilets or faucets, missing or defective PRV, water billestimates, low pressure, water heater malfunction, well pump issues,and/or other issues with the plumbing system 116 can be displayed at thepoint interfaces 124.

The user device 130 can be any tablet, cellular telephone, web browser,or other interface to the water analysis system 100. The water device120 is enrolled into a user account with the user device 130. All theinformation available at a point interface 124 can be made available tothe user device using an application, app and/or browser interface. Theuser device 130 can wired or wirelessly connect with the water device(s)120, cloud analyzer 108, and/or point interface(s) 124.

With reference to FIG. 2, a block diagram of an embodiment of a waterdevice 120 is shown. A power supply 220 could be internal or external tothe water device 120 to provide DC power to the various circuits. Insome embodiments, a replaceable battery provides power while otherembodiments use the water pressure to drive a turbine that recharges abattery to provide power.

An analysis engine 204 gathers various data from the pressure sensor(s)240, flow sensor(s) 244, temperature sensor(s) 248, and optionally audiosensor(s) 250. Interface pages 216 allow interaction with the waterdevice 120 through a network interface 208 in a wired or wirelessfashion. The analysis engine 204 also supports a unit interface 212 thatis physically part of the water device 120 to display various status,information and graphics using an OLED, LED, LCD display and/or statuslights or LEDs.

Various information is stored by the water device 120, which may bereconciled with the cloud analyzer 108 in-whole or in-part using thenetwork interface 208. Sensor data for the various sensors 240, 244,248, 250 are stored in the sensor data store 228 over time to allow forlongitudinal analysis. For example, several hours through several daysof sensor data can be stored. The granularity of readings and length oftime stored may be predefined, limited by available storage or changebased upon conditions of the plumbing system 116. For example, datasamples every second over a two day period could be stored, but when aleak is suspected the sample rate could increase to 60 times a secondfor 4 hours of time.

When fixtures or appliances interact with the water in the plumbingsystem 116, repeating patterns occur at the water device 120. Patternprofiles 224 are stored to quickly match current sensor readings toknown events. For example, a particular faucet when used may cause theflow, pressure and/or temperature sensor 244, 240, 248 readings tofluctuate in a predictable manner such that the pattern profile can bematched to current readings to conclude usage is occurring. ApplicationSer. No. 14/937,831, entitled “WATER LEAK DETECTION USING PRESSURESENSING,” filed on Nov. 10, 2015, describes this analysis and isincorporated by reference for all purposes. The pattern profiles 224 canbe in the time domain and/or frequency domain to support variouscondition matching by the analysis engine 204. Both intentional egressand leaks have pattern profiles 224 that are stored.

A configuration database 232 stores information gathered for the waterdevice 120. The Table depicts water supply parameters stored in theconfiguration database 232. Type of plumbing system 116 includes thosewithout a PRV, well water, working PRV, and non-functional PRV. Thewater supply to the water main 150 can be from the municipal watersystem 128, a well, a water tank, or other source. The configurationdatabase 232 can be automatically populated using algorithms of theanalysis engine 204 or manually entered by the user device 130.Different fixtures and appliances connected to the plumbing system 116are noted in the configuration database 232.

TABLE Water Supply Field Options Type No PRV Well water Working PRVNon-Functional PRV Supply Municipal water Well Tank

Referring next to FIG. 3, a block diagram of an embodiment of a cloudanalyzer 108 is shown. The cloud analyzer 108 receives data andconfiguration information from many buildings 112 throughout the wateranalysis system 100. Each building 112 has a system profile 224 that isstored including the fixtures, appliances, water device(s) 120, pointinterface(s) 124, type of water supply, water source type are stored.Account information 232 including login credentials, building location,and user demographic information is also stored. Gathered sensor data inraw and processed form is stored as analyzer data 228 and could includeusage history, specific egress events, leaks detected, etc.

The system analyzer 204 can process the data from each building 112 tofind patterns corresponding to leaks, malfunctions, and other eventsthat are not recognized by the water device 120 locally. The systemanalyzer 204 can access any water device 120 or point interface 124 totest functionality, update software, and gather data. Where a userdevice 130 is coupled to the cloud analyzer 108, the system analyzer 204receives commands to perform requested tasks. For example, the userdevice 130 can query for usage on a per fixture or appliance basis.Overall usage can also be determined. The system analyzer 204 can accessthe water utility usage and billing to provide insights into costs andoverall consumption. For those utilities that provide usage informationin real time, the usage and cost can be determined for each use of theplumbing system 116.

An account interface 216 allows various water devices 120 and userdevices 130 to interact with the cloud analyzer 108 through an internetinterface 208. The cloud analyzer 108 provides historical and real timeanalysis of buildings 118 a user is authorized to access. Variousinteraction pages allow entry of plumbing system information,configuration parameters, building location and user demographicinformation. Various reports and status parameters are presented to theuser device through the account interface 216.

With reference to FIG. 4, a block diagram of an embodiment of a plumbingsystem 116 is shown. The municipal water system 128 is connected to amain shutoff valve 412-1 before the water main passes through a watermeter 404 provided by the municipality for billing purposes. The watermeter 404 may be electronically or manually read to determine the bill,but some embodiments allow real time reading of the water meter 404electronically.

Building codes often require use of a PRV 408, but not universally.Older homes may also be missing a PRV, have one that no longer functionsproperly or have less than 80 psi supplied by the municipal water system128. A building shutoff valve 412-2 is often located interior to thebuilding 112 and provides another place to close off the water main. Awater device 120 is located after the building shutoff valve 412-2, butbefore a water heater 416 in this embodiment. The water device 120 canbe placed under the sink, near an appliance or any other location wherefluid coupling is convenient along with a source of power is nearby. Thehot water pipes 424 provide heated water to the building 118 and thecold water pipes 420 provide unheated water varying between the ambienttemperature in the building 112 and the temperature of the municipalwater system 128.

This embodiment has a single bathroom 428, a kitchen 432, a washingmachine 436, and a water spigot 440, but other embodiments could havemore or less fixtures and appliances. The bathroom 428 has a shower 444,sink 448, bathtub 452, and toilet 456 that use water. The sink 448,bathtub 452, and shower 444 are all hooked to both the hot and coldwater pipes 424, 420. The toilet 456 only requires cold water so is nothooked to the hot water supply.

The kitchen 432 includes a two-basin sink 460, a refrigerator withliquid/ice dispenser, and a dishwasher. The refrigerator only receivescold water 420, but the two-basin sink 460 and dishwasher 468 receiveboth cold and hot water 420, 424. Kitchens 432 commonly includesingle-basin sinks and other appliances that might be coupled to thewater.

Referring next to FIG. 5, a diagram of an embodiment of an installedwater device 500 is shown. The water device 120 passes water through apipe 420 that is integral to the water device 120 and attached on bothends to either a hot or a cold water line. The integral portion of thepipe 420 could be made of copper, PVC, plastic, or other building pipematerial and could be mated to the plumbing system 116 with solderedjoints, glued joints, and/or detachable and flexible hoses.

There are several modules that make up the water device 120. The powersupply 220 powers the water device 120 and could be internal or externalto the enclosure. A network module 520 includes the network interface208 to allow wired or wireless communication with the network 134 andInternet 104 to other components of the water analysis system 100. Adisplay assembly 522 includes the unit interface 212.

Another module is the circuit card 536 which performs the processing forvarious sensors. Sensor information can be processed on the circuit cardusing the analysis engine 204 and/or processed in the cloud using thesystem analyzer 204. Sensor information is gathered and analyzed overhours and days to find weak signals in the data indicating usage, leaksand other issues. The circuit card 536 might recognize sensor samples ofinterest and upload those to the cloud analyzer 108 for deeper learning.The circuit card and cloud analyzer can use artificial intelligence,genetic algorithms, fuzzy logic, and machine learning to recognize thecondition and state of the plumbing system 116.

This embodiment includes three temperature sensors 512 to measure theambient temperature with a sensor near the outside of the enclosure andaway from the internal electronics and water temperature of the water inthe pipe 420 in two locations. A first temperature sensor 512-1 measureswater temperature in contact with the water as it enters the pipe 420 ofthe water device 120 away from any heat that the various circuits mightgenerate. A second temperature sensor 512-2 measures water temperatureat a second location away from the first temperature sensor 512-1. Basedupon readings of the two water temperature sensors 512-1, 512-2, theheat generated by the water device 120 can be algorithmically correctedfor. Some embodiments may only use a single water temperature sensorand/or forgo the ambient temperature sensing. Ambient temperature may bemeasured by other equipment in the building and made available over thenetwork 134, for example, the thermostat, smoke detectors, pointinterface(s) 124 can measure ambient temperature and provide it to otherequipment in the building 112.

This embodiment includes an electronically actuated shut-off valve 532.The shutoff valve 532 can be used to prevent flooding for leaksdownstream of the water device 120. Additionally, the shutoff valve 532can aid in detecting leaks. Closing the shutoff valve 532 and detectinga falling pressure is indicative of a leak downstream. Some embodimentscan partially close the shutoff valve 532 to regulate pressuredownstream.

A flow sensor 528 is used to measure the flow in the pipe 420. In thisembodiment, an ultrasonic flow sensor is used, but other embodimentscould use a rotameter, variable area flow meter, spring and piston flowmeter, mass gas flow meters, turbine flow meters, paddlewheel sensors,positive displacement flow meter, and vortex meter. Generally, thesemeters and sensors cannot measure very small flows in a pipe in apractical way for building deployments.

The circuit card 536 is coupled to a pressure sensor 524 coupled to thewater in the pipe 420. Readings from the pressure sensor are used totest the PRV, well pump, water supply, and pipe for leaks as well asidentify normal egress from the water fixtures and appliances. Pressureand temperature vary with flow such that the pressure sensor 524 andtemperature sensor 512-1, 512-2 can be used to detect flow as small astiny leaks under certain circumstances. The circuit card 536 observestrends in the sensor data, performs spectral analysis, pattern matchingand other signal processing on the sensor data.

With reference to FIG. 6A, a chart 600-1 showing an embodiment of a leakcondition is shown with temperature data over time. In a situation wherethe building 112 is warmer than the water supply, flow in the plumbingsystem 116 will cause the temperature to fall from the ambient indoortemperature 608 to the water supply temperature 604. The slope of thefall increases with the spread in temperature difference and the rate ofconsumption from the municipal water system 128. Algorithms to detectleak only activate when intentional usage is not present.

Referring next to FIG. 6B, a chart 600-2 showing an embodiment of a noleak condition is shown with temperature data over time. The measuredtemperature in the plumbing system 116 will generally rise to theambient indoor temperature 608 in the absence of any intentional flow orany leak. Typically, the sensor readings are far noisier than depictedin the charts which show a highly smoothed version.

With reference to FIG. 7A, a chart 700-1 showing an embodiment of a leakcondition is shown with pressure data over time. There is a pressurethreshold 708 for houses with a PRV or well where the water main or wellpump will activate when the pressure in the plumbing system 116 fallsbelow the pressure threshold 708. With intentional usage or a leak, thepressure will drop until the plumbing system 116 is pressurized by thePRV opening or the pump activating.

Referring next to FIG. 7B, a chart 700-2 showing an embodiment of a noleak condition is shown with pressure data over time. Generally, theplumbing system 116 will remain pressurized so long as there is nointentional or unintentional egress. For buildings without a PRV, thepressure fluctuates as neighbors and other users of the municipal watersystem 128 activate their fixtures and appliances.

With reference to FIG. 8, a flow chart of an embodiment of a process 800for detecting leaks is shown. The depicted portion of the process 800begins in block 802 where the water device 120 is configured. Thisincludes installation that couples the water device 120 physically tothe plumbing system 116. Power is run to the water device 120 along witha connection to the network 134. The water device 120 is enrolled intoan account with the cloud analyzer 108. Information about the building112, demographic information about the account owner, etc. are allentered with the user device 130.

Once the physical installation and account configuration is done, thewater device 120 is configured to detect the topology of the plumbingsystem 116 in block 804. Using signal processing the user activates eachfixture and appliance in succession to enroll its signature. Over time,the water device 120 in conjunction with the cloud analyzer 108processes sensor data to more accurately detect intentional wateregress. In block 804, the flow sensor detects new flow. Where determinedto be normal intentional egress in block 808 the responsible waterfixture(s) and/or appliance(s) responsible are determined in block 812.The usage is recorded in block 816. The sensor data, usage, leaks arelogged at the water device 120. In block 820, relevant sensor readings,processed information and any errors and leak conditions are reported tothe cloud analyzer 108. Push or pull messages are sent to the userdevice 130 for any leaks, abnormal usage or other errors.

Where the egress is not determined normal in block 808, processingcontinues to block 832. Abnormal egress 808 is where the flow sensor 528detects flow that doesn't correspond to any known fixture or appliance.This could correspond to a change in the plumbing system 116 so when theuser receives the error, they can correct the system noting the changeto the plumbing system 116 to avoid false alarms in the future.Processing continues after the suspect leak is detected in block 832 toblock 820.

Where there is no flow detected by the flow sensor back in block 804,small leak detection is performed. In block 838, the algorithm used fortesting varies upon what type of water supply and water source. Forexample, the algorithm used for well water is different from one usedfor a building using the municipal water system without a PRV being forthe building 112. The various pressure and temperature sensors 524, 512gather data over time in blocks 840 and 844 as separate processes. Thesensor readings are analyzed using various signal processing techniquesin block 848 as fully detailed in FIGS. 9A-9C below. Where a small leakis detected processing continues to block 820 and to block 804 where noleak is detected.

Referring next to FIG. 9A, a flow chart of an embodiment of a process900A for analyzing temperature sensor 512 readings is shown. Thisprocess 900A runs continuously where there is no intentional egressdetected. The process 900A may run in parallel to leak detection usingpressure sensor data as described in FIGS. 9B and 9C below. Either thetemperature sensing or pressure sensing can independently result in aleak determination in this embodiment. But, other embodiments score eachparallel determination and weigh those scores to produce a combinedscore that results in a leak determination when the composite score isbeyond a composite threshold.

The depicted portion of the process begins in block 901 where a rollingwindow of temperature data is loaded into the analysis engine 204. Thewindow can be 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours ormore in different embodiments. Where there is a change in ambienttemperature that would affect measurement of the water in the plumbingsystem 116, it is corrected for in block 903. The temperature inside thebuilding 112 or outdoors can affect the water temperature in the pipes.A model of those changes is built over time for different temperaturetrends so that it can be removed from the data in block 903. In thisembodiment, a transient peak typically appears near the beginning of adownslope in temperature readings as the water falls to the water supplytemperature 604 and those transient peaks are detected in block 905. Theduration of the downsloping trend is tested in block 909. Where thetrend is too small, it is discarded in block 913 as the window ofanalysis moves forward through the temperature data before looping backto block 901. A downtrend less than 10, 20, 40 60, or 90 minutes isdiscarded in various embodiments.

Where the downtrend is of the correct duration as determined in block909, the right portion of the window is analyzed for stability in block917. Generally, leaks are consistent, stable and occasionally increasingin flow. A determination is made in block 921 of whether the rightportion of the window is stable and consistent in its downslope. Wheredetermined unstable in block 921, processing loops back to block 901.When the right portion of the window is stable processing continues toblock 925 where a leak is determined before rolling forward in the datain block 913 to look for more leak conditions. This process continuessuch that small leaks are continuously searched for when there is nointentional egress from the plumbing system 116. Some embodiments relyon temperature sensing to detect leaks, while other embodiments usepressure sensing as explained below, still other embodiments use bothtemperature and pressure sensing algorithms to detect leaks in parallel.

Referring next to FIGS. 9B and 9C, a flow charts of an embodiment of aprocess 900B, 900C for analyzing pressure sensor 524 readings is shown.Two different types of pressure sensor analysis are possible dependingon whether the building 112 has a PRV or well water. With referenceinitially to FIG. 9B, the depicted portion of the process begins inblock 902 where a rolling window of pressure data is loaded foranalysis. This embodiment begins the pressure sensor 524 analysis afterthree hours of the pressure readings that do not register anyintentional egress from the plumbing system 116. Other embodiments couldhave a different period such as 2, 4, 5, 6, or 7 hours. Where it isdetermined in block 908 that the water supply type is well water,processing goes to block 950 of FIG. 9C.

Where there is a PRV to buffer spectral components of pressure from themunicipal water system 128 or well water supply as determined in block908, processing continues to block 912 for an initial calibrationpresumably where there is no leak condition. Should a leak be determinedwith the temperature sensing algorithm of FIG. 9A, the calibration isdiscarded and performed again where there is no leak. In block 912, thepressure sensor data is converted to the frequency domain. Over thesensor window, the energies are averaged at each frequency in block 914before normalization in block 918. The spectrogram of the plumbingsystem 116 without a leak once determined can be removed from futurespectral analysis.

At a time after initial calibration to determine the background spectra,the spectra for the possible leak region is determined in block 916 forthe pressure sensor 524 data in the window. The frequency domain valuesare normalized in block 924. The background spectra are removed from thepossible leak spectra in block 928. The remaining spectral componentsare analyzed in block 932. The remaining spectral components can beadded together to see if it exceeds a predetermined threshold. The leakadds unique spectral components that when present and over a thresholdare determined a leak in block 936. Where a leak is not determined,processing loops back to block 902 to roll the analysis window forwardin time.

Referring next to FIG. 9C, a flow chart 900C for an embodiment of a leakdetection algorithm is shown that is used for buildings 112 using wellwater. Typically, a PRV is not present when on a well, but a pump isused to pull the well water from the ground. A pump in the well pumpswater through one or more check valves and into the building 112. Whenthere is no water demand, the check valve(s) is closed to maintain aconstant pressure in the plumbing system 116. As egress occurs, pressurein the plumbing system 116 decreases until a cracking pressure opens thecheck valve(s) to supply more water. When the lower limit of thepressure threshold is reached, the pump activates to pressurize theplumbing system 116 and supply well water. Where there is intendedegress or a leak, the pressure varies in a saw tooth pattern over time.The depicted portion of the process 900C begins in block 950 where a twohour window of pressure sensor readings are loaded for analysis. Otherembodiments could load windows of different sizes.

The pressure readings are smoothed in block 976 before splitting thewindow into smaller frames of thirty seconds. Other embodiments coulduse 15, 45, 60, 90, 120, or 150 second frames. Each of the frames hasits slope determined in block 984. Any frames corresponding to the pumpbeing active are filtered out along with frames without significantenough slope that it could be a leak in block 986. What remains areframes that have a slope that corresponds to a leak condition.

In block 988, the frames that are possible leaks are counted, and thatcount is compared with a threshold. Where the count is below athreshold, the variance in pressure is attributed to noise andprocessing loops back to block 962 where the window is discarded beforefetching another window. Where a significant count exists of frames thathave slopes like a leak above a threshold, a leak is determined in block974 before looping back to block 962.

A number of variations and modifications of the disclosed embodimentscan also be used. For example, the plumbing analyzer can be used tomonitor any liquid distributed in pipes. This could include industrialplants, sprinkler systems, gas distribution systems, refineries,hydrocarbon production equipment, municipal water distribution, etc. Theplumbing system is a closed system with pressurized liquid (e.g., a gas)that is released in a selective and controlled manner using valves.

In systems where there is no PRV or a poorly functioning one, leaks canbe detected by shutting off the water supply to the plumbing system. Thepressure will fall off from the plumbing system as the water leaks fromthe plumbing system. Shutting off the water supply can be done by thewater device in some embodiments. As shut off can be inconvenient tooccupants, this test can be done at times where normal egress isunlikely to happen. When normal egress does happen, the water supply canbe turned on again to quickly provide for normal egress. In someembodiments, when leaks are detected with the algorithms in FIGS. 9A-9Cthat conclusion might be confirmed with a pressure test after shut offof the water.

Pressure will change with thermal expansion of the plumbing system 116.With the pipes largely being in the walls of the building 112, they areaffected by the interior and exterior temperatures. The interiortemperature can be measured at the water device 120 or throughcommunication with the HVAC system and the exterior temperature can bedetermined using the location of the building 112 with third partyweather information. The effect of thermal expansion as a function ofthese the delta of these two temperatures can be modeled over time. Insome embodiments, the effect of thermal expansion is removed from thepressure sensor readings, for example, homes with functioning PRVs.

Specific details are given in the above description to provide athorough understanding of the embodiments. However, it is understoodthat the embodiments may be practiced without these specific details.For example, circuits may be shown in block diagrams in order not toobscure the embodiments in unnecessary detail. In other instances,well-known circuits, processes, algorithms, structures, and techniquesmay be shown without unnecessary detail in order to avoid obscuring theembodiments.

Implementation of the techniques, blocks, steps and means describedabove may be done in various ways. For example, these techniques,blocks, steps and means may be implemented in hardware, software, or acombination thereof. For a hardware implementation, the processing unitsmay be implemented within one or more application specific integratedcircuits (ASICs), digital signal processors (DSPs), digital signalprocessing devices (DSPDs), programmable logic devices (PLDs), fieldprogrammable gate arrays (FPGAs), processors, controllers,micro-controllers, microprocessors, other electronic units designed toperform the functions described above, and/or a combination thereof.

Also, it is noted that the embodiments may be described as a processwhich is depicted as a flowchart, a flow diagram, a swim diagram, a dataflow diagram, a structure diagram, or a block diagram. Although adepiction may describe the operations as a sequential process, many ofthe operations can be performed in parallel or concurrently. Inaddition, the order of the operations may be re-arranged. A process isterminated when its operations are completed, but could have additionalsteps not included in the figure. A process may correspond to a method,a function, a procedure, a subroutine, a subprogram, etc. When a processcorresponds to a function, its termination corresponds to a return ofthe function to the calling function or the main function.

Furthermore, embodiments may be implemented by hardware, software,scripting languages, firmware, middleware, microcode, hardwaredescription languages, and/or any combination thereof. When implementedin software, firmware, middleware, scripting language, and/or microcode,the program code or code segments to perform the necessary tasks may bestored in a machine readable medium such as a storage medium. A codesegment or machine-executable instruction may represent a procedure, afunction, a subprogram, a program, a routine, a subroutine, a module, asoftware package, a script, a class, or any combination of instructions,data structures, and/or program statements. A code segment may becoupled to another code segment or a hardware circuit by passing and/orreceiving information, data, arguments, parameters, and/or memorycontents. Information, arguments, parameters, data, etc. may be passed,forwarded, or transmitted via any suitable means including memorysharing, message passing, token passing, network transmission, etc.

For a firmware and/or software implementation, the methodologies may beimplemented with modules (e.g., procedures, functions, and so on) thatperform the functions described herein. Any machine-readable mediumtangibly embodying instructions may be used in implementing themethodologies described herein. For example, software codes may bestored in a memory. Memory may be implemented within the processor orexternal to the processor. As used herein the term “memory” refers toany type of long term, short term, volatile, nonvolatile, or otherstorage medium and is not to be limited to any particular type of memoryor number of memories, or type of media upon which memory is stored.

Moreover, as disclosed herein, the term “storage medium” may representone or more memories for storing data, including read only memory (ROM),random access memory (RAM), magnetic RAM, core memory, magnetic diskstorage mediums, optical storage mediums, flash memory devices and/orother machine readable mediums for storing information. The term“machine-readable medium” includes, but is not limited to portable orfixed storage devices, optical storage devices, and/or various otherstorage mediums capable of storing that contain or carry instruction(s)and/or data.

While the principles of the disclosure have been described above inconnection with specific apparatuses and methods, it is to be clearlyunderstood that this description is made only by way of example and notas limitation on the scope of the disclosure.

What is claimed is:
 1. A method for detecting leaks of liquid in aplumbing system, the method comprising: measuring a set of pressure dataover time within a pipe of the plumbing system; processing the set ofpressure data to divide the set of pressure data into a plurality offrames; for each frame of the plurality of frames: determining amagnitude of a slope of the pressure data within the frame; andprocessing the magnitude of the slope to determine whether the slopecorresponds to a leak condition; processing the plurality of frames todetermine whether a function of a sum of the slopes that correspond tothe leak condition exceeds a threshold; and transmitting a leak detectedsignal if the function exceeds the threshold, wherein the leak detectedsignal indicates that there is a leak in the plumbing system.
 2. Themethod as recited in claim 1, further comprising filtering out a subsetof the plurality of frames that correspond to a period during which apump connected to the plumbing system was active.
 3. The method asrecited in claim 1, further comprising using signal processingtechniques to determine that the plumbing system is connected to a well.4. The method as recited in claim 1, further comprising, beforemeasuring the set of pressure data: measuring liquid flow within thepipe of the plumbing system with a flow sensor; and determiningalgorithmically using the flow sensor that there is no intentionalliquid egress from the plumbing system caused by an open water fixture.5. The method as recited in claim 4, wherein flow through the leak inthe plumbing system is below a perceptible limit of the flow sensor. 6.The method as recited in claim 1, wherein the function of the sum of theslopes that correspond to the leak condition is a count of the slopesthat correspond to the leak condition.
 7. A device for detecting leaksof liquid in a plumbing system, the device comprising: one or moreprocessors; and one or more memories, wherein the one or more memorieshave machine readable instructions to: measure a set of pressure dataover time within a pipe of the plumbing system; process the set ofpressure data to divide the set of pressure data into a plurality offrames; for each frame of the plurality of frames: determine a magnitudeof a slope of the pressure data within the frame; and process themagnitude of the slope to determine whether the slope corresponds to aleak condition; process the plurality of frames to determine whether afunction of a sum of the slopes that correspond to the leak conditionexceeds a threshold; and transmit a leak detected signal if the functionexceeds the threshold, wherein the leak detected signal indicates thatthere is a leak in the plumbing system.
 8. The device as recited inclaim 7, the one or more memories further having instructions to filterout a subset of the plurality of frames that correspond to a periodduring which a pump connected to the plumbing system was active.
 9. Thedevice as recited in claim 7, the one or more memories further havinginstructions to use signal processing techniques to determine that theplumbing system is connected to a well.
 10. The device as recited inclaim 7, the one or more memories further having instructions to, beforemeasuring the set of pressure data: measure liquid flow within the pipeof the plumbing system with a flow sensor; and determine algorithmicallyusing the flow sensor that there is no intentional liquid egress fromthe plumbing system caused by an open water fixture.
 11. The device asrecited in claim 10, wherein flow through the leak in the plumbingsystem is below a perceptible limit of the flow sensor.
 12. The deviceas recited in claim 7, wherein the function of the sum of the slopesthat correspond to the leak condition is a count of the slopes thatcorrespond to the leak condition.